1. Field of the Invention
The present invention relates to an information processing apparatus having a built-in hard disk drive and a head retraction processing method of the built-in hard disk drive.
2. Description of the Related Art
In a portable device such as a note-type PC, it is an important problem to be solved to protect the device against shock in cases like the device is mistakenly dropped or the shock is applied from the outside when the device is carried by hand or being in use. In particular, in a magnetic disk drive such as a hard disk drive (HDD) used as a recording device, a magnetic head reads and writes data from and to a rotating magnetic disk. Thus, when the magnetic head collides with the magnetic disk due to shock or vibration applied to the device, the magnetic disk may be damaged and data recorded thereon may be destroyed. Although an acceleration sensor may be built into the HDD, in many cases, the HDD is merely designed to stop writing data on the disk temporarily and even if the head is being retracted, the operation of the head may not be controlled precisely.
To solve this problem, an acceleration sensor or the like may be built into the device and when the acceleration or its change amount that the acceleration sensor detects exceeds predetermined level, the magnetic head is retracted to a data-free landing zone.
In a related art of this kind, a system that stops writing data to the record medium temporarily when the HDD is subjected to shock or vibration may be adopted. When the HDD stops writing data to the record medium, data may be prevented from being written to an incorrect address, however, since the head is placed above the medium, the head may contact the medium, when the head is subjected to strong shock or vibration. As a result, there is a possibility that the head being damaged.
To solve such a problem, in a related art of such kind, a sensor such as an acceleration sensor may be used to detect shock or vibration applied to the HDD. When the sensor detects shock or vibration, the HDD retracts the head to the data-free landing zone. For example, according to Japanese Patent Application Laid-Open publication No. 2005-346840 the falling state of the device is detected based on acceleration for the X axis, Y axis, and Z axis and when the state is detected, the head of the HDD is retracted to the data-free landing zone.
However, the acceleration sensor is a device that detects acceleration, namely a change of speeds per unit time. Thus, if a shock/vibration determination process is performed on the basis of only the levels of acceleration information obtained from the sensor, the magnetic head may be unnecessarily retracted, which leads to decrease of user-friendliness. For example, if the head is retracted while music data or video data are being reproduced from the HDD, video or sound may be temporarily stopped. Alternatively, vibration caused by pressing a key of a build-in keyboard of the device or shock caused by closing a lid that has a display section and that can be opened and closed from and to the main body of the device may result in unnecessarily retracting the magnetic head and thereby decreasing user-friendliness.
Generally, the acceleration sensor is a device that provides acceleration information. Thus, it is necessary to use a dedicated shock/vibration processing section that is used to determine whether or not the HDD is subjected to shock or vibration. To implement this section, by for example a PC, a program (driver) that operates on an operating system (OS) or a dedicated LSI may be provided.
However, when the shock/vibration determination is performed with the program (driver) that operates on the OS, due to characteristics of the PC, resources of the CPU are inevitably used. It is necessary to perform the shock/vibration determination in real time. Thus, the CPU use rate increases and, as a result, the power consumption of the device increases. For the note-type PC, it is important to decrease the power consumption thereof as much as possible to prolong the battery life, therefore, an increase in power consumption is a serious problem.
In contrast, when the dedicated LSI is build-into the device, not only the power for the LSI, but the area for the LSI and a peripheral circuit are necessitated, which leads to a larger circuit scale and increase in cost.